Custom Cactus Soil Mix

Discuss repotting, soil, lighting, fertilizing, watering, etc. in this category.
bartab
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Re: Custom Cactus Soil Mix

Post by bartab »

Well, just curious about what people think about a 50/50 mix for cactus in Charleston. I would be worried about having to much potting soil mix. You might want to think about that. I wouldn't use any for cactus, and use a little with your succulents. I would not use a regular potting soil, but rather something like palm and citrus mix, or something others would recommend.
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Steve Johnson
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Re: Custom Cactus Soil Mix

Post by Steve Johnson »

bartab wrote: Mon Jul 15, 2019 7:08 am Well, just curious about what people think about a 50/50 mix for cactus in Charleston. I would be worried about having to much potting soil mix. You might want to think about that. I wouldn't use any for cactus, and use a little with your succulents. I would not use a regular potting soil, but rather something like palm and citrus mix, or something others would recommend.
You bring up a really good point. Victoryboxer, I live in a fairly humid coastal microclimate, and if anything, your climate may be even more humid than mine. Once again, I think you would do well going soil-less with your cacti -- if your instinct leads you to adding some soil, a 50/50 mix will be way too heavy on the soil. I think an 80/20 mineral-to-soil mix would be okay for your cacti, but don't be afraid of trying the soil-less approach!

Bartab is right about needing soil in the mix for succulents. My summers are generally in the 80s, so the 50/50 mix I use for my Haworthia is just fine. If Charleston's summers are hotter and more humid, an 80/20 or 70/30 mineral-to-soil mix may be about right for succulents. That's just a guess, so when in doubt, ask for advice on the Succulent Growing help forum.
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victoryboxer
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Re: Custom Cactus Soil Mix

Post by victoryboxer »

Thanks y'all for the advice!! I'm going to do the 80/20 mineral to soil mix fir the cacti and probably 60/40 for my succulents. I'm also going to do the top layering, I have found a lot of cool stones on Amazon that I'm going to use. Think that one of my Golden Barrels is going to look great with red tigers eye stones all around it. Appreciate the thoughts guys!!
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Edwindwianto
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Re: Custom Cactus Soil Mix

Post by Edwindwianto »

rsz_20191204_100330.jpg
rsz_20191204_100330.jpg (88.62 KiB) Viewed 10364 times
Is this sand considered a clay loam?
It feels gritty and crumbly
Idk what type of sand that is

I would consider it for my arios, if it were a clay loam
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greenknight
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Re: Custom Cactus Soil Mix

Post by greenknight »

Can't tell just by looking at it. The way to test it is to shake it up with water in a jar, the different constituents will settle out at different rates and you can measure the different layers. See: https://hgic.clemson.edu/factsheet/soil ... -jar-test/
Spence :mrgreen:
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Edwindwianto
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Re: Custom Cactus Soil Mix

Post by Edwindwianto »

greenknight wrote: Wed Dec 04, 2019 5:29 am Can't tell just by looking at it. The way to test it is to shake it up with water in a jar, the different constituents will settle out at different rates and you can measure the different layers. See: https://hgic.clemson.edu/factsheet/soil ... -jar-test/
Thanks GK
keith
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Re: Custom Cactus Soil Mix

Post by keith »

Iann wrote this I would agree. Whatever happened to him anyway ?

Mineral soils for all US cacti, many Mexican species, particularly from Baja, Chilean species, and possibly more. Often these are adapted to limestone, although not in Baja or Chile. There are a few of these that certainly grow on somewhat organic soils in habit, for instance Pediocactus simpsonii on pine litter, but still want a mineral soil in cultivation.

Brazilian species prefer a more acidic soil, often quite organic, and also many other South Americans including Gymnocalyciums. There are still some species found on limestone, but I don't have all the details on the South Americans. Some Andean species in particular may want a soil with more humus than I give them, although some certainly don't. Epiphytes and many other jungle types obviously like an organic soil.
DaveW
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Re: Custom Cactus Soil Mix

Post by DaveW »

Iann's on the British Cactus & Succulent Society Forum most of his time these days Keith being a Brit.

https://forum.bcss.org.uk/viewtopic.php?f=1&t=169850

https://forum.bcss.org.uk/viewforum.php ... 30990cbd7c
keith
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Re: Custom Cactus Soil Mix

Post by keith »

The big question about soils whatever you mix is how long should it stay damp after watering? 1 day ? 1 week ? 1 month ? I will go for 1-2 weeks and after 2 weeks it should be dry to the touch at least. What drys out in 2 days in Phoenix AZ might take 2 months in England or Oregon.
bartab
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Re: Custom Cactus Soil Mix

Post by bartab »

How long do you want to keep the roots of Mexican cacti damp?
keith
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Re: Custom Cactus Soil Mix

Post by keith »

I transplanted a few 10 year old Ariocarpus fissuratus that were in 2 1/4 rose pots , 3 in a pot and 4 in a pot yea they are small, and the soil was damp at the root and I haven't watered for a couple weeks so that's too wet IMO . I GUESS too much dry stall pumice. I mentioned before I have cut all new soil with course gravel 1/4" -1/8" size. better safe than sorry.

The old soil that was damp looked like it had a small amount of redish dirt in it so IDK what I had years ago when I planted them in the little pots ? I have a vague memory of lava rock fines ? Little plants can take more dampness they were not rotted but once they get old and big you have to be really careful . Same goes for Lithops, plus other Mexcian living rock type cactus the types with big roots. Other kinds of cactus I'm not sure .

Anyway after a watering in a few weeks I want dry soil. 1 week might be too quick but I'm not sure ? I'm also growing Basil in a pot but that's a completely different story. :D
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Steve Johnson
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Re: Custom Cactus Soil Mix

Post by Steve Johnson »

keith wrote: Tue Jun 23, 2020 6:13 pm I transplanted a few 10 year old Ariocarpus fissuratus that were in 2 1/4 rose pots , 3 in a pot and 4 in a pot yea they are small, and the soil was damp at the root and I haven't watered for a couple weeks so that's too wet IMO.
Yep, that mix should've been completely dry when you did the transplant, so there's something wrong with the mix. Give me a breakdown of the ingredients and approximate percentage of each ingredient going into your mix, and I may be able to give you some halfway decent feedback

By the way, I've found from personal experience that mineral fines like decomposed granite "play sand" (or in your case lava rock) and pumice dust are a lousy substitute for soil. Sandy loam soil is ideal, although I don't know where we can even find it.
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keith
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Re: Custom Cactus Soil Mix

Post by keith »

Hi Steve got some pictures for ya. and my thoughts.

Pictures of latest rot I have had way too much this year. I think too much pumice. It looks dry but I think it holds water inside the porous struture which is why people like it. Beside Mexican living rock type cactus I lose lithops too. Other kinds of cactus seem to like it better than old sandy mix . But I mostly grow these difficult living rock types this is turbincarpus valdezianus.

I think the 60-40 is probably a good choice pumice to gravel so I added more gravel to my pumice.
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ROT
ROT
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ROT same pot
ROT same pot
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good no rot
good no rot
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new mix more rocks less pumice
new mix more rocks less pumice
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Steve Johnson
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Re: Custom Cactus Soil Mix

Post by Steve Johnson »

Let's compare notes here, Keith...

The humidity in my part of L.A. 6/17-6/24 ranged from 52% to 84%, about 70%-75% on average. I kinda assumed that Thousand Oaks is a drier climate, but when we look at your humidity during the same period, it was 55%-90%, about 75%-80% on average. That really surprised me. Darryl Craig at CoronaCactus Nursery was the one who recommended a 60/40 pumice/granite gravel mix to me in 2012. His reason for the granite gravel was to make the pots heavier so they don't tip over in a strong wind. Definitely more of a problem for him (and you) than it is for me, although my place can get awfully windy at times, and that's why I went with his recommendation. The mix in my pots goes from wet to bone dry all the way down in about 7 days, so what you and I are finding out together is that straight pumice does take too long to dry out in a rather humid climate like ours. Sorry you had to find out the hard way -- IMO the 60/40 pumice-to-gravel mix I use should be the right choice for you too.

By the way, drying-out times are pretty much the same regardless of pot size -- something else I found rather surprising when I used a digital scale to weigh pots with different sizes going from wet to dry a number of years ago.
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My location: Los Angeles, CA (Zone 10b)
keith
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Re: Custom Cactus Soil Mix

Post by keith »

Thanks Steve that's what I think too- more gravel. I checked a bunch of little pots by tipping the top stones out and looking at the soil all pots were dry but one , Weird all watered about 3 weeks ago. Some of these pots are years old and I can see the different styles of soil I've used over the years and the wet pot when it dries I will spread it out and see what I had going on ? Wet but no rot . The pumice can be dry ( feels dry) and rot.

Its like the pumice stays wet and they goes dry by the time I see the problem ( exponential drys out like really wet for days then absorbs the water and is dry to the touch) and the sandy soil just sort of dries out on a linear curve. Cant hold as much water. In Phoenix AZ this was not a problem super hot and dry.
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